Neurofibromatosis type 1 (NF1) is an autosomal dominant disease affecting chromosome 17. It is manifested by a neurogenic tumor proliferation that forms cutaneous, subcutaneous or deep neurofibromas.

Neurofibromas can cause functional discomfort, neurogenic pain that is difficult to treat, and severe cosmetic disorders.

Treatment is essentially surgical. It is sometimes a heavy invasive surgery with complicated postoperative follow-up and significant scarring on the aesthetic level. Currently, no systemic treatment has proven its effectiveness in this pathology.

Percutaneous cryotherapy is a cold thermoablation procedure using fine 17 G needles introduced into the lesion after targeting by imaging. This technique is used in the treatment of soft tissue tumors and desmoid tumors.

The treatment of neurofibromas with percutaneous cryotherapy is not well known. Encouraging results (unpublished) have been observed in patients with NF1 treated with cryotherapy at the Léon Bérard Center. The beneficial effect was observed in terms of quality of life (in particular, pain) as well as a decrease in tumor size.

On the basis of this first experience, it appears important to corroborate these preliminary results by a prospective study allowing the use of this technique to treat patients with unresectable or resectable neurofibromas but with mutilating surgery in a NF1 context.

Inclusion Criteria:

• Age ≥18 years;
• Patient with neurofibromatosis type 1 according to NIH criteria ;
• Patient with a benign neurofibromatous lesion that is painful and/or generates functional discomfort and is unresectable or with unacceptable scarring ;
• Neutrophils > 1 G/l in the 14 days prior to inclusion;
• Adequate coagulation test with normals values (as judged by the investigator);
• Signed and dated informed consent document indicating that the patient has been informed of all aspects of the trial prior to enrolment
• Covered by a medical insurance;

Exclusion Criteria:

• Patient treated with concomitant chemotherapy and/or targeted therapies ;
• Any contraindication to a percutaneous cryotherapy procedure, including the need for ice formation within 1 cm of the spinal cord, brain or other critical nerve structures, bowel or bladder (unless active or passive thermal protective maneuvers are performed);
• Patient with malignant neurofibroma or MPNST ; CT scan without abnormality and if tumor presents a max SUV T/F>1.5 ratio, targeted biopsy is required to confirm benign or malignant histology.
• Patient with neurofibroma in areas at risk for neurological sequelae;
• Patient with cold urticaria with history of angioedema;
• Any cognitive impairment or condition that may limit the use of numerical scales and quality of life questionnaires;
• Patient for whom follow-up does not seem feasible even in the short term;
• Participation in another clinical trial that may interfere with the evaluation of the primary endpoint;
• Patient under tutorshio, curatorship or deprived of liberty;
• Pregnant or breast-feeding woman;
• Any contraindication to the performance of an MRI
• Patient with dysplastic neurofibroma